SiC single crystals are thermally and chemically very stable, superior in mechanical strength, and resistant to radiation, and also have superior physical properties, such as high breakdown voltage and high thermal conductivity compared to Si single crystals. They are therefore able to exhibit high output, high frequency, voltage resistance and environmental resistance that cannot be realized with existing semiconductor materials, such as Si single crystals and GaAs single crystals, and are considered ever more promising as next-generation semiconductor materials for a wide range of applications including power device materials that allow high power control and energy saving to be achieved, device materials for high-speed large volume information communication, high-temperature device materials for vehicles, radiation-resistant device materials and the like.
A variety of different measures have been taken to produce high-quality low-resistance p-type SiC single crystals, in order to obtain ultra-high voltage-resistant elements that are considered promising for applications in electrical power systems and the like. PTL 1 proposes a method for producing a p-type SiC single crystal by a solution process using a Si—C solution containing 0.1 to 20 at % Al based on the total amount of Si, Cr and Al.